What Happens After Drilling Through the Unsaturated Zone?
When drilling a water well, one of the most critical steps is transitioning from the unsaturated zone (vadose zone) to the saturated zone, where a high-yield aquifer begins. Understanding this transition is key to ensuring your well delivers a reliable, abundant water supply.
The Unsaturated Zone: The First Layer
The unsaturated zone lies above the water table and consists of soil, clay, caliche, gravel, and fractured rock. Here, the spaces between particles are only partially filled with water—mostly air and moisture from rain or runoff.
While drilling through this zone is necessary, it does not provide usable water. Its main role is to allow safe penetration down to the aquifer, where groundwater is fully contained.
Entering the Saturated Zone and High-Yield Aquifers
Once the drill passes through the unsaturated zone, it enters the saturated zone, where groundwater completely fills rock and sediment. This is the aquifer, the source of your water.
Key Features of a High-Yield Aquifer:
- Consistent Water Availability: Water is fully saturated in rock and sediment, ensuring reliable supply.
- Depth and Formation: The depth and type of rock or sand determine water yield and well productivity.
- Optimized Water Flow: Professional drilling targets the most productive sections of the aquifer to maximize gallons-per-minute (GPM).
Typical Aquifer Depths in Arizona
The depth of a high-yield aquifer varies depending on local geology:
- St. Johns: 150–400 ft
- Phoenix Basin: 700–1,200+ ft
- Tucson: 300–800 ft
Accurately reaching these depths requires professional expertise to ensure the well taps into the highest-yielding section of the aquifer.
Steps to Maximize Yield from a High-Yield Aquifer
After entering the saturated zone, the goal is to maximize water yield and secure a long-term, reliable supply:
- Drill Deeper Into the Aquifer: Access the sections with the highest water availability.
- Install Well Casing & Screens: Protects the well from sediment while allowing clean water in.
- Gravel Pack & Annular Seal: Stabilizes the well and prevents surface contamination.
- Air Development & Cleaning: Optimizes water flow and removes fine sediments.
- Pump Installation: High-efficiency pumps ensure steady water delivery from the aquifer.
Why Professional Water Well Drilling Matters
DIY rigs and kits cannot reliably reach high-yield aquifers, especially in Arizona’s challenging geology. Professional water well contractors ensure:
- Accurate targeting of the aquifer using seismic and geophysical testing
- Compliance with ADWR regulations
- Proper well construction, casing, and pump installation
- Maximum water yield and long-term reliability
Drilling through the unsaturated zone is just the start. Reaching a high-yield aquifer ensures your well delivers abundant, dependable groundwater for years to come.
If you’re in Phoenix, St. Johns, Tucson, or anywhere in Arizona, trusting professional water well contractors is the sure-fire way to access high-yield aquifers safely and efficiently.
Ready to tap into a high-yield aquifer? Contact Arizona Well Drilling LLC today to secure a reliable water source for your home, farm, or business.
